Páginas

01 October, 2018

Enzymatic fructosylation of hydroxytyrosol: reaction and mechanism

We have investigated the ability of the β-fructofuranosidase pXd-INV from the yeast Xanthophyllomyces dendrorhous to glycosylate the olive biophenol hydroxytyrosol (HT). Two fructosylated derivatives (Fru-HT1 and Fru-HT2) were synthesized.MS and 2D-NMR analyses showed that the major product (Fru-HT1) was fructosylated at the primary OH of HT. The structure of the complexes with the substrates and the product analyzed by crystallography led to the understanding of the molecular determinants regulating the enzymatic mechanism. Product-soaked crystals revealed that the minor derivative (Fru-HT2) was fructosylated at the phenolic p-OH group. One of the studied mutants (N342Q) was notably more specific for the fructosylation at the phenolic OH than the wild-type.